This paper outlines effects of the usage of two plant growth promoting (PGP) strains: Bacillus sp.
strain Q3 and Pseudomonas chlororaphis strain Q16 trough vegetative experiments, performed in
semi-controlled conditions on acid soils (Lessivated Cambisols). The studied parameters were chemical
properties of soil and PGP effects of strains and their mixture on two wheat (Triticum aestivum L.)
cultivars - NS 40S and CCB Ingenio. The seeds treatments with Q3 reduced the occurrence of Blumeria
graminis f.sp. tritici natural infection only on CCB Ingenio (46.1%). The additional foliar treatment
with Q3 decreased disease incidence (DI) 76.22% (CCB Ingenio) and 75.87% (NS 40S). Reduced
initial DI of 77% caused Q16 solely or mixed with Q3 on cv. NS 40S and additional foliar treatment
reduced DI to 16.30% (CCB Ingenio) and to 6.35% (NS 40S). The mixture of strains decreased DI to
14.69% (CCB Ingenio) and to 6.09% (NS 40S). Despite the effects of applied strains on wheat growth
were affected by limited production capacity of soil and the extreme climatic conditions, SDW of
inoculated cultivars were increased by 17-39% (NS 40S) and 35-43% (CCB Ingenio). The N increment
ranged from 59% (Q3) to 152% (Q16) for cv. CCB Ingenio. Finding that the seeds treatments improved
the plant biomass and N content (Q16) and decreased powdery mildew DI, we can recommended
application of Q16 strain as biofertilizer for both wheat cultivars. Depending on wheat cultivar, the
additional foliar treatments to prevent powdery mildew infection will be set up for further trials